Round electric cable for severe environmental operation and method of manufacture thereof

ABSTRACT

A method is herein provided for making round electrical cable for use under severe environmental conditions including the step of providing a conductor, coated with a layer of insulating material. A lead sheath is applied over the layer of insulating material and a layer of heat resistant, abrasive resistant, protective material, such as a nylon base substance, is extruded onto the outer surface of the lead sheath. The conductor is then twisted with other similar conductors, through a die, and the bundle of mutually twisted conductors is then encased in a nitrile-base jacketing material. The disclosed round cable generally includes a plurality of mutually twisted, insulated conductors, encased in a nitrile-base jacket. Each insulated conductor generally comprises at least one strand of conductor wire, coated with an electrical insulating material and a lead sheath enclosing the insulating material. A layer of an abrasive resistant protective material is applied to the outer surface of the lead sheath. Preferably, the protective material consists of a nylon-based relatively pliable substance.

United States Patent [191 Pearson 1 1 ROUND ELECTRIC CABLE FOR SEVERE ENVIRONMENTAL OPERATION AND METHOD OF MANUFACTURE THEREOF [75] Inventor: Stanley Pearson, Trenton, NJ.

[73] Assignee: Crescent Insulated Wire & Cable Company, Inc., Trenton, NJ.

[22] Filed: Nov. 13, 1972 211 App]. No.: 305,800

[52] US. Cl 174/103, 156/50, 174/107 [51] Int. Cl. H0lb 7/20 [58] Field of Search l74/l02 R, 107, 103, 116,

174/110, 110 PM, 133 R, 120 SR; 57/7, 9;

[56] References Cited UNITED STATES PATENTS 1,083,258 12/1913 Kitsee 174/103 1,702,332 2/1929 Apt l74/l07 1,904,873 4/1933 Marvuson.... 174/107 2,427,507 9/1947 Powell 57/7 2,509,894 5/1950 Toulmin 174/ l28 UX I FOREIGN PATENTS OR APPLICATIONS I 18,805 0/1883 Great Britain 174/103 217,045 9/1941 Switzerland 174/110 N OTHER PUBLICATIONS Product Applications Highlight Ten Desireable Properties of DuPont Zytel Nylon Resin Brochure of Du- Pont, Wilmington, Del. 1955.

[451 May 7,1974

Brady, Materials Handbook McGrawl-lill, New York, 1966, p. 795.

Primary Examiner-E. A. Goldberg Attorney, Agent, or Firm-Sperry and Zode [5 7 ABSTRACT A method is herein provided for making round electrical cable for use under severe environmental conditions including the step of providing a conductor, coated with a layer of insulating material. A lead sheath is applied over the layer of insulating material and a layer of heat resistant, abrasive resistant, protective material, such as a nylon base substance, is extruded onto the outer surface of the lead sheath. The conductor is then twisted with other similar conductors, through a die, and the bundle of mutually twisted conductors is then encased ina nitrile-base jacketing material.

The disclosed round cable generally includes a plurality of mutually twisted, insulated conductors,

encased in a nitrile-base jacket. Each insulated conductor generally comprises at least one strand of conductor wire, coated with an electrical insulating material and a lead sheath enclosing the insulating material. A layerof an abrasive resistant protective material is applied to the outer surface of the lead sheath. Preferably, the protective material consists of a nylon-based relatively pliable substance.

5 Claims, 4 Drawing Figures BACKGROUND OF THE INVENTION The present invention relates to a high temperature electric cable which is particularly suitable for downhole, pumping operations, and the like.

In such cable configurations, it is common to have at least three conductors bound together as a conductor bundle in either a mutually twisted or in a side-byside disposition. Examples of such high temperature electric cables are set forth in the disclosure of US. Pat. No. 3,413,408, issued to Robinson, on Nov. 26, 1968, and assigned to the assignee of the present invention.

Typically, it has been found that, when the conductors are bound together in a side-by-side, flat cable, configuration, more installation damage is probable, due to crushing, catching, and abrasion in a borehole, than if the conductors were mutually twisted into a round" cable.

Due to the various electrical fields created by three phases of an electrical power supply being carried by three adjacent conductors, it has been found highly desirable to configure the conductor bundle in a mutually twisted arrangement so as to minimize and balance the effects of the electrical fields created thereby. When the conductors are aligned in a side-by-side configuration, electrical imbalances have resulted'in phase shifts and other undesirable electrical phenomena. Additionally, since many boreholes, in earth drilling operations, deviate from a normal plumb line to a substantial degree, the restricted flexibility of a flat cable, in the plane of flatness, presents a problem to those attempting to supply electrical power down hole.

Accordingly, it is advantageous, from both a physical and an electrical viewpoint, to be able to readily form conductor bundles in a mutually twisted configuration, as a round cable. However, since such conductors are generally covered witha lead sheathing, and since the lead sheathing may become severely abraded, during a twisting operation, through a die, such twisting of lead sheathed high temperature fore been difficult.

Therefore, it would be a major contributionto the art, if a method and apparatus were provided for facilitating the mutual twisting of conductors, covered with lead sheaths, for the purpose of forming high temperature cable.

OBJECTS AND SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a method and apparatus for facilitating the mutual twisting of conductors having lead sheaths disposed thereon.

It is another object of the present invention to facilitate the manufacture of round cable.

It is still another object of the present invention to provide a method and apparatus for manufacturing cable which tends to minimize the effect of the mutual interaction of electrical fields of a plurality of contiguous electrical conductors.

It is a major object of the present invention to solve at least some of the problems confronting those atconductors has heretotempting to provide electrical power down-hole in pumping operations.

The above-cited objects are achieved by the provision of a method for making round, high temperature electrical cable including the step of providing a conductor, coated with a layer of electrical insulating material. A lead sheath is applied over the layer of electrical insulating material and a layer of heat resistant, abrasive resistant, relatively pliable protective material is applied to the outer surface of the lead sheath. The conductor is then'mutually twisted with'other similar conductors, through a die, and the resulting conductor bundle is encased in a nitrile base jacketing material.

The insulated conductor, according to the present invention, generally comprises at least one strand of conductor wire coated with an electrical insulating material and a lead sheath enclosing the overall conductor, so insulated. A layer of abrasive resistant'protective material is applied onto the outer surface of the lead sheath to prevent abrasion of the lead sheath during mutual twisting of the conductor with other similar conductors, through a die.

- BRIEF DESCRIPTION OF THE DRAWINGS While the invention is particularly pointed out and distinctly claimed in a concluding portion of the specification, a preferred embodiment is set forth in the following detailed description, which may be: best understood when read in conjunction with the accompanying drawings, in which:

FIG. 1 is a radial sectional view of a round cable according to present invention;

FIG. 2 is a perspective view of the round cable, set forth in FIG. 1, wherein various layers of material have been stripped away to illustrate the general components of the overall cable;

FIG. 3 is a diagrammatic view of protective material being extruded, in accordance with one method of the present invention; and

'FIG. 4 is a diagrammatic view, illustrating the step of mutually twisting conductors, according to the present invention, to form a conductor bundle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, in which like numerals are used to indicate like parts throughout the various views thereof, FIG. 1 shows a radial sectional view of a round cable according to the present invention.

- Essentially, the cable comprises a plurality of insulated conductors 10, which may each, in turn, comprise a plurality of conductor strands 12. The strands 12 mayfor extreme environmental conditions, a lead sheath 16 is disposed about the insulated conductors 10.

In accordance with the present invention, a heat resistant, abrasion resistant, protective, relatively pliable material 18 is extruded over the outer surface of the lead sheath 16. The method of applying the material 18 3 as well as the function thereof will be explained, in detail, with respect to FIGS. 3 and 4.

The mutually twisted bundle of conductors is then encased within an oil-resistant, gas-resistant, and water-resistant jacket material 20, such as Acrylonitrilebutadiene (Nitrile). Sometimes, a flexible, interlocked galvanized steel or monel armor is applied over the nitrile jacket for additional mechanical protection. However, this is not always necessary.

In particular, it has been found that, while such armor is necessary when the conductors 10 are aligned side-by-side, as a flat bundle, which is subject to crushing and abrasion within a borehole, a round cable, such as shown in FIG. 1, is less susceptible to crushing and abrasion so as to permit the. cable to be effectively utilized without the addition of such armor.

FIG. 2 shows the components set forth in FIG. 1, in a stripped-away perspective view.

Referring now to FIG. 3, a conductor 10, having a lead sheath l6 enclosing the conductor, is passed through an extruding apparatus 22. The conductor may pass through acentral portion of the extruding apparatus 22 and the protective material 18 may be applied to the outer surface of the lead sheath 16 so as to provide an abrasion-resistant, relatively pliable, high temperature, protective coating for the lead sheath 16. One example of a substance which has been found to work entirely satisfactorily is plasticized nylon material, sold by Rilsan Corporation of I39 Harristown Road, Glen Rock, N.J., and identified as Rilsan Nylon 1 l, BESNO- P40. The lubricity of nylon makes this substance especially effective. Additionally, the nylon is compatible with the nitrile jacket material 20.

Referring now to FIG. 4, it can be. seen that three reels 24, 26, and 28 carrying the protectively coated conductors (individually lead-sheathed and coated with the plastic covering 18) are disposed to rotate so as to mutually twist the protectively coated conductors 30, 32, and 34. Since the conductors must be twisted into a tight bundle 36, a mechanical die 38 is provided for guiding the conductors into a proper bundle configuration. v

Heretofore, ithad been found that the lead sheath 16 may become distorted and severely'abraded, during this mutual twisting operation, as the conductors 30, 32, and 34 are forced through the die 38.

I have discovered that, by applying a substance having the requisite properties of pliability, resistance to abrasion, and ability to withstand high temperatures, such as the plasticized-nylon identified above, to the outer surface of the lead sheath 16, the distortion and abrasion of the lead could be prevented. This, in turn, was found to prevent electrical and mechanical failures caused when cable, utilizing distorted and abraded lead sheathed conductors, is subjected to the severe, environmental conditions of down hole operations.

The coating 18 applied about each lead sheath protectively encases the same in a manner that is of particular importance during the manufacture of the cable, in that first of all it permits the making of a round cable having mutually twisted conductors that are lead sheathed; secondly, accomplishes this by utilizing a protective coating for the conductors applied to the lead-sheathed conductors by an extrusionprocess or by an equally inexpensive method; and third, in the completed cable is fully compatible with the nitrile jacket thereof and has other important physical properties Water absorption:

saturation at 73F. and 65% R 0.3%

24 hr. at 73F l .l% Tensile strength:

at -40 F 9,500 psi at +68 F 7,500 psi at +l76 F 5,000 psi Elongation:

at --40 F at +68 F 300% Taber Abrasion:

C17 wheel, 1,0000. Wt.

loss in. mg, .1000 cycles-2 F lexural Modulus:

It is entirely possible that other materials, having physical and electrical properties equal or in general close to those tabulated above, may be employed. For

example, those extrusion-grade products classed as thermoplastic polyurethane compounds would be usable as the coating 18 selected of course to incorporate the requisite heat resistance, the toughness, and the pliability possessed by the nylon product hereinbefore identified. Typical among these, the polyester polymer sold under the trandemark ESTANE 5710 by the B-.F. Goodrich Chemical Company, 3135 Euclid Ave., Cleveland, Ohio 44115 may be advantageously employed. s i

Also usable is the 90 Shore A polytetrame'thylene etherglycol (PTMG) based thermoplastic, polyurethane material known as ROYLAR E-9 and sold by Uniroyal Chemical Division of Uniroyal, Inc., Naugatuck, Connecticut 06770.

It can therefore be seen that a conductor configuration has been herein provided which facilitates the mutual twisting of conductors for the manufacture of round cable. Furthermore, it can be seen that amethod for manufacturing round cable has been herein disclosed which method permits the formation of conductor bundles in a tight, mutually twisted configuration, so as to minimize the mutual interaction of fields, created by current flowing through mutually adjacent conductors.

It can also be seen that, since cablejfor severe environmental conditions may .now be made in a round configuration, without the difficulty heretofore experienced, the flat type of cable configuration, need not be used. This, in turn, permits effective use of deviated boreholes. Also, the severe crushing offlat cable and the abrading thereof, caused by the rather cumbersome configuration of the flat cable, may now be obviated by the use of round cables.

In sum, the invention produces, at a competitive production cost, a cable that has lead-sheathed conductors to withstand extreme environmental conditions; that has desirable electrical properties through the provision' of spirally twisted conductors; has desirable mechanical properties as regards withstanding crushing and distortion in use; has good flexibility to facilitate insertion and withdrawal from the hole; and has compatible components all of which can withstand severe environmental conditions. To my knowledge, all of these characteristics have heretofore not been combined in a single cable.

Accordingly,gthe present invention is a technical advanceand a contribution to the field of electrical cables especially adapted for manufacture'of a round cable having a multiplicity of spirally twisted lead-sheathed conductors, and for use in the severe environmental conditions associated with down hole pumping operations.

SCOPE OF THE INVENTION While what has been described is a preferred embodiment of the present invention, it is of course to be understood that various modifications and changes may be made therein without departing from the invention.

Accordingly, it is intended to cover in the following claims all such modifications and changes as may fall within the true spirit and scope of the present invention.

What I claim is:

l. A method for making round electrical cable comprising the steps of:

first, providing a conductor, coated with a layer of electrical insulating material; then, applying to saidconductor a lead sheath over the layer of electrical insulating material;

after application of said lead sheath, applying a layer of heat resistant, abrasive resistant, relatively pliable, protective material onto an outer surface of the sheath whereby to prevent distortion and abra- 6 sion of said sheath normally likely to occur on twisting of a plurality of lead-sheathed conductors together;

then, mutually twisting the conductor with the lead 1 sheath and said layer of pliable material thereon, with other similar conductors to which lead sheaths and pliable material have also been applied, through v a die; and as a final step,

encasing the twisted conductors in a jacketing material.

2. A round electrical cable comprising:

a bundle of mutually twisted insulated conductors en cased in a jacket, each said insulated conductor comprising at least one strand of conductor wire coated with an electrical insulating material and a lead sheath enclosing the insulated conductor wire; and

a now impregnated covering of an abrasive resistant,

heat-resistant, relatively pliable, protective material, completely enclosing the lead sheath of each of the mutually twisted conductors of said bundle, the several lead-sheath-enclosing coverings of the bundle extending in longitudinally contacting relation in the twisted relationship of the conductors whereby to prevent distortion and abrasion of the lead sheaths normally likely to occur on twisting of a plurality of conductors together when they are so sheathed. I

3. The combination according to claim 2, wherein said abrasive resistant, heat resistant, relatively pliable, protective material comprises a nylon base.

4. The combination, according to claim No. 2 wherein said abrasive resistant, heat resistant, relatively pliable, protective material exhibits a high degree of lubricity.

5. The combination according to claim 2, wherein said abrasive resistant, heat resistant, relatively pliable,

protective material comprises a polyurethane base.

C UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2.809.802 Dated Mav 7. 197 1 Inventor(s) Stanley Pearson It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6 line 19 change "now" to non 1 Signed and sealed this 1st day of October 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Atte'sting Officer Commissioner of Patents USCOMM-DC 6037 6-F'69 FORM PO-1050 (10-69) u.s. eovsnuyuwr mnmns orncs: um o-see-au,

UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION Patent 3.809.802 Dated Mav 7. 197M Inventor(s) Stanley Pearson It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 19 change "now' to --non-- Signed and sealed this 1st day of October 1974.

(SEAL) Attest:

McCOY M. GIBSON JR. C. MARSHALL DANN Attesting Officer Commissioner of Patents USCOMM-DC 60316-P69 w u.s. aovzmmzm PRINTING OFFICE is o-ass-au,

F ORM PO-105O (10-69) 

2. A round electrical cable comprising: a bundle of mutually twisted insulated conductors encased in a jacket, each said insulated conductor comprising at least one strand of conductor wire coated with an electrical insulating material and a lead sheath enclosing the insulated conductor wire; and a now impregnated covering of an abrasive resistant, heat resistant, relatively pliable, protective material, completely enclosing the lead sheath of each of the mutually twisted conductors of said bundle, the several lead-sheath-enclosing coverings of the bundle extending in longitudinally contacting relation in the twisted relationship of the conductors whereby to prevent distortion and abrasion of the lead sheaths normally likely to occur on twisting of a plurality of conductors together when they are so sheathed.
 3. The combination according to claim 2, wherein said abrasive resistant, heat resistant, relatively pliable, protective material comprises a nylon base.
 4. The combination, according to claim No. 2, wherein said abrasive resistant, heat resistant, relatively pliable, protective material exhibits a high degree of lubricity.
 5. The combination according to claim 2, wherein said abrasive resistant, heat resistant, relatively pliable, protective material comprises a polyurethane base. 